Method of forming centers



J. H. DOWNIE. METHOD OF FORMING .CENTERS. ORIGINAL FILED SEPT. 15, 1919.

Feb. 5, 1923.

Patented Feb. e, was.

UNTTEH STATilti PATENT JAMES E. DOWNIE, OF SAN ANTONI O, TEXAS.

METHOD OF FORMING CENTERS.

Original application filed September 15, 1919, Serial No. 323,756.Iiivided and this application filed September 2, 1921. Serial No.498,058.

T all whom it may concern.

Be it known that 1, James H. DOWNIE, a citizen of the United States,residing at San Antonio, in the county of Bexar, State of Texas, haveinvented certain new and useful Improvements in Methods of FormingCenters; and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will. enable others skilledin the art to which it appertains to make and use the same.

This invention relates to centering ma chines and is a division from myapplication for patent for improvements in center forming devices, filedSept. 15, 1919, Ser. No.

The object of the invention is to produce a machine by means of whichthe exact center in the end .of a shaft or similar piece of rotatingwork can be found and turned so that the work can subsequently be putonto a lathe for turning.

In constructing a centering machine in accordance with the presentinvention, 1.

provide a bed having a single pair of ways, instead of double as thoseof an ordinary turning lathe. At one end of the ways is a head stock,having a hollow spindle, on which is mounted 'a chuck to receive thework to be centered.

I mount on the ways a work support similar to the well known universalchuck, but which does not rotate, the jaws of the chuck being adjustedto hold the work only with such pressure as to prevent chattering,forming a bearing in which the end of the shaft to be centered rotates.

Upon the ways is mounted a carriage corresponding to the tail stock of alathe and 4 upon which is mounted a member that is adjustabletransversely of the bed end which in turn carries a turret, the base ofwhich is adjustable thereon longitudinally of the bed while the body ofthe turret is rot-atably adjustable as is usual.

The turret is provided with three tools, of which the first one to bebrought into action is a facing tool that faces the end of the work atright angles to its axis of lo tation. The next tool is a grooving toolwhich when presented to the work, has its point eccentric to the axis ofrotation of the work, so as to cut an annular groove concentric to theaxis of rotation. The third tool is a stationary drill which ispresented to the work with its axis alined with the axis of rotation ofthe work and which serves to cut out the material within the enclosureof the outer wall of the groove and which wall is, of course, concentricto the axis of rotation. The result is a conical bearing seat in the endof the work, the curved wall of which is concentric to the axis ofrotation. The bearing seat thus provided is a true concentric seatwhether or not the drill was presented concentric to the axis of rotation of the work.

Details of one manner of successfully carrying out this invention areset forth low, and reference is made to the drawings wherein Figure 1 isa side elevation of this machine.

Figure 2 is a plan view of the right end of Figure 1, on a larger scale,showing the free end of the work in section.

In the drawings, a machine is shown as having a bed 1 provided with ways2, illlt power is communicated from a suitable source to the pulleys 3fast on a tubular shaft 4 ournaled 1n bearings 5 rising from said bed,the shaft carrying a chuck 6 b means of which the work is grasped androtated. The work is here shown as a metal rod or shaft S and if longerthan illustrated in Figure 1, it could be extended through the tubulardriving shaft and held in the left hand chuck 7. On the ways is mountedthe base of a turret whose parts are adjustable transversely andlongitudinally of the bet in the usual or any well known manner, and

this turret carries the tools.

I prefer to guide the free end of the work S by a second chuck numbered.8, which is a non-revolving, universal, threeawed structure whose jawsare simultaneously moved as usual by a mechanism not necessary to showand describe in detail. 'The support 9 for this chuck holds it upon andabove the ways 2 so that its true axis is in exact alinement with thetrue axis of the driving chuck 6. The jaws in the latter arr adjusted togrip one end of the work f5 whereas the jaws in the chuck 3 are adustedto a point where they serve as a guide for the other end of the work.

The turret may be of any appropriate construction and is mounted uponthe block 1 which in turn is mounted on the base 10 that is slidablelongitudinally of the bed 1. The block 14 has the usual dove-tail connection with the base 10 for adjustment transversely thereof through themedium of the adjustingscrew. 30 that is operated by the crank 81. Theturret has also a dovetail connection with the upper face of the block14 along which it is adjustable of the bed 1 through the medium of theusual adjusting screw 32 having an operating crank 33. These adjustmentsare well known to those skilled in the art and will not require specificillustration.

It is the base 15 of the turret that is slidably mounted in the block 14and this base has a vertical cylindrical post. 16 on which is rotatablymounted a head 17 carrying the tools that are herein described. The headof the turret is illustrated as cylindrical and it is held in itsdifferent angular adjustments by the usual spring bolt 18, the lower endof which engages the member 15 and the upper end of which bolt isprovided with a knob 19 to facilitate raising of the bolt from themember 15 to permit of angular adjustment of the turret head.

Mounted in and standing radial to the head 17 are three tools, onenumbered 21 being the turning tool and having a V- shaped point 22,another number 23 being the finishing tool and having a rather bluntdrill point 2 1, and a third being the facing tool 25 with a roundedpoint 26. These several tools may be mounted in the head in any suitableway, but are preferably held under set screws 27 as usual, and thefacing tools are shown as diametrically opposite and standing on astrictly radial line through the center of the head, while the roughingtool 21 is shown as disposed between the other two and a little off astrict radial line which would pass from the center of the post 16 alongthe true axis of the work S as clearly seen in Figure 2. it will beunderstood that the element 15 is provided with sockets for the tip ofthe bolt 18 which are so located that the tool selected may be caused toproject toward the work, which is to the left in both views.

From the base 10 rises a lip or flange 11 through which is screwed astop screw 12 provided with a jam nut 13 for holding it at times againstrotation, the free end of the screw being directed toward the block 14so that it may be positioned to limit movement of the block with theturret transversely of the bed 1, to position with either of the tools23 and 25 centered with the work when the turret is correspondinglyadjusted.

In the use of the machine, a piece of work which in the present instanceis shown as a shaft S, is engaged atone end in the chuck 6 and is passedbetween the jaws of the positioning chuck S, the jaws of which are thenadjusted so as to hold the shaft against chattering but to permit of itsrotation. The turret is then turned to bring the facing tool 25 with itsaxis parallel to the axis of rotation of the work and by manipulation ofthe screw 32 through the medium of its handle 33, the turret is shiftedto bring the facing tool up to the work. Then, through the medium of thescrew 80 and its handle 31, the block 1 1 with the turret is fedtransversely of the bed 1 to carry the facing tool across the end of theshaft so as to give it a flat face to facilitate such treatment by thetool 21. The turret is then shifted to the position shown in Figure 2and is advanced to engage the point 22 of the tool 21 with the end faceof the shaft at a point eccentric to the axis of rotation of the shaft.The point 22 being tapered, it cuts an annular groove in the end face ofthe shaft, illustrated in Figure 2, which groove is, of course,concentric with the axis of rotation ofthe shaft and which axis ofrotation is approximately central to the periphery of the shaft byreason of the positioning chuck 8. This annular groove that the tool 21cuts, has both its inner and outer walls tapered and when the toolbecomes initially active, there is within the enclosure of the groove aresultant frusto-conical boss, which becomes first conical and thendiminishes in altitude andbase diameter as the tool advances. When thegroove has been cut to the proper depth, at which time the altitude ofthe conical boss is materially less than the depth of the groove, thetool is withdrawn, and the turret is rotated to direct the drill 23toward the work and with its axis parallel thereto. By manipulation ofthe screw 30 through the medium of its handle 31, the block 1 1 is thenfed transversely of the bed 1 until it contacts with the screw 12, whichas above stated, is adjusted so that under such condition, the drill 23will be centered with the work or in other words will be in axialalinement therewith. Thus, this transverse adjustment may beaccomplished without the ex ercise of special care as the screw 12 willterminate the transverse adjustment with the drill in axial alinementwith the work.

The axis of the drill intersects the axis of rotation of the turret andthe drill engages the central boss and cuts it entirely away, thediameter of the drill being greater than the base diameter of theconical boss that has been left. The drill is then withdrawn and theresult is a socket in the end of the work, every section through thewall of which socket in planes perpendicular to the axis of rotation ofthe work, is either a complete and true circle if the drill was axiallyalined with the work or is in the arc of a true circle if the axis ofthe drill was parallel to but at one side of the axis of the work. It is01"- course understood that if the axis of the drill 23 has not beenabsolutely alined with the work and its annular groove, the inner end ofthe tapered socket is not in a plane at right angles to the axis of thesocket, but on the contrary, is at a slight angle thereto. Thesecomplete circles or arcs, as the case may be, being of constantlydecreasing radii inwardly of the socket, it will be understood that abearing will be presented for the dead center of the lathe, which isshaped to correspond to the angularity of the wall of the socket.

lVhat is claimed is:

The method of centering a piece of work for subsequent turning whichconsists in rotating the work about an axis passing through itpresenting a grooving tool to an end face of the work eccentric to itsaxis of rotation with the cutting of an annular groove and removing thematerial within the enclosure bounded by the groove to a planematerially inwardly of the outer edge of the outer wall of the groove.

In testimony whereof, I afiix my signature.

JAMES H. DOVVNIE.

